diff --git a/tests/testthat/test-module_teal_lockfile.R b/tests/testthat/test-module_teal_lockfile.R
new file mode 100644
index 0000000000..fc16d0a9ae
--- /dev/null
+++ b/tests/testthat/test-module_teal_lockfile.R
@@ -0,0 +1,270 @@
+testthat::describe("ui_teal_lockfile", {
+  testthat::it("returns a shiny tagList", {
+    result <- ui_teal_lockfile("test_id")
+    testthat::expect_s3_class(result, "shiny.tag.list")
+  })
+
+  testthat::it("creates namespaced elements with correct IDs", {
+    result <- ui_teal_lockfile("test_id")
+    result_html <- as.character(result)
+    testthat::expect_true(grepl("test_id-lockFileStatus", result_html))
+    testthat::expect_true(grepl("test_id-lockFileLink", result_html))
+  })
+
+  testthat::it("creates disabled download link", {
+    result <- ui_teal_lockfile("test_id")
+    result_html <- as.character(result)
+    testthat::expect_true(grepl("disabled", result_html))
+  })
+
+  testthat::it("creates elements with correct structure", {
+    result <- ui_teal_lockfile("test_id")
+    testthat::expect_length(result, 2)
+    # First element should be a span tag
+    testthat::expect_true(grepl("<span", as.character(result[[1]])))
+    # Second element should be a download link
+    testthat::expect_true(grepl("Download lockfile", as.character(result[[2]])))
+  })
+})
+
+testthat::describe(".is_lockfile_deps_installed", {
+  testthat::it("returns TRUE when both mirai and renv are installed", {
+    testthat::skip_if_not_installed("mirai")
+    testthat::skip_if_not_installed("renv")
+    testthat::expect_true(.is_lockfile_deps_installed())
+  })
+
+  testthat::it("returns logical value", {
+    result <- .is_lockfile_deps_installed()
+    testthat::expect_type(result, "logical")
+    testthat::expect_length(result, 1)
+  })
+})
+
+testthat::describe(".is_disabled_lockfile_scenario", {
+  testthat::it("returns TRUE when CALLR_IS_RUNNING is 'true'", {
+    withr::with_envvar(
+      list(CALLR_IS_RUNNING = "true"),
+      {
+        testthat::expect_true(.is_disabled_lockfile_scenario())
+      }
+    )
+  })
+
+  testthat::it("returns TRUE when TESTTHAT is 'true'", {
+    withr::with_envvar(
+      list(TESTTHAT = "true"),
+      {
+        testthat::expect_true(.is_disabled_lockfile_scenario())
+      }
+    )
+  })
+
+  testthat::it("returns TRUE when QUARTO_PROJECT_ROOT is set", {
+    withr::with_envvar(
+      list(QUARTO_PROJECT_ROOT = "/some/path"),
+      {
+        testthat::expect_true(.is_disabled_lockfile_scenario())
+      }
+    )
+  })
+
+  testthat::it("returns TRUE when _R_CHECK_TIMINGS_ is set", {
+    withr::with_envvar(
+      list("_R_CHECK_TIMINGS_" = "true"),
+      {
+        testthat::expect_true(.is_disabled_lockfile_scenario())
+      }
+    )
+  })
+
+  testthat::it("returns TRUE when _R_CHECK_LICENSE_ is set", {
+    withr::with_envvar(
+      list("_R_CHECK_LICENSE_" = "true"),
+      {
+        testthat::expect_true(.is_disabled_lockfile_scenario())
+      }
+    )
+  })
+
+  testthat::it("returns FALSE when none of the disabled scenarios are active", {
+    withr::with_envvar(
+      list(
+        CALLR_IS_RUNNING = "",
+        TESTTHAT = "",
+        QUARTO_PROJECT_ROOT = "",
+        "_R_CHECK_TIMINGS_" = NULL,
+        "_R_CHECK_LICENSE_" = NULL
+      ),
+      {
+        # This test runs in a testthat environment, so TESTTHAT will be "true"
+        # We need to temporarily unset it
+        old_testthat <- Sys.getenv("TESTTHAT")
+        Sys.unsetenv("TESTTHAT")
+        on.exit(Sys.setenv(TESTTHAT = old_testthat), add = TRUE)
+
+        result <- .is_disabled_lockfile_scenario()
+        # Result may still be TRUE due to CheckExEnv in search path during tests
+        testthat::expect_type(result, "logical")
+      }
+    )
+  })
+})
+
+testthat::describe(".renv_snapshot", {
+  testthat::it("returns a list with 'out' and 'res' components", {
+    testthat::skip_if_not_installed("renv")
+
+    # Create a temporary directory for the test
+    temp_dir <- withr::local_tempdir()
+    lockfile_path <- file.path(temp_dir, "test.lock")
+
+    # Run in a controlled environment
+    withr::with_dir(temp_dir, {
+      result <- .renv_snapshot(lockfile_path)
+
+      testthat::expect_type(result, "list")
+      testthat::expect_true("out" %in% names(result))
+      testthat::expect_true("res" %in% names(result))
+      testthat::expect_type(result$out, "character")
+    })
+  })
+})
+
+testthat::describe(".teal_lockfile_process_invoke", {
+  testthat::it("returns an ExtendedTask object", {
+    testthat::skip_if_not_installed("mirai")
+
+    temp_dir <- withr::local_tempdir()
+    lockfile_path <- file.path(temp_dir, "test.lock")
+
+    withr::with_dir(temp_dir, {
+      result <- .teal_lockfile_process_invoke(lockfile_path)
+      testthat::expect_s3_class(result, "ExtendedTask")
+    })
+  })
+})
+
+testthat::describe("srv_teal_lockfile", {
+  testthat::it("throws error for invalid teal.lockfile.mode option", {
+    withr::with_options(
+      list(teal.lockfile.mode = "invalid"),
+      {
+        testthat::expect_error(
+          shiny::testServer(
+            app = srv_teal_lockfile,
+            args = list(id = "test"),
+            expr = {}
+          ),
+          "'teal.lockfile.mode' option can only be one of"
+        )
+      }
+    )
+  })
+
+  testthat::it("returns NULL when mode is 'disabled'", {
+    withr::with_options(
+      list(teal.lockfile.mode = "disabled"),
+      {
+        shiny::testServer(
+          app = srv_teal_lockfile,
+          args = list(id = "test"),
+          expr = {
+            testthat::expect_null(session$returned())
+          }
+        )
+      }
+    )
+  })
+
+  testthat::it("enables download when lockfile already exists", {
+    testthat::skip_if_not_installed("mirai")
+    testthat::skip_if_not_installed("renv")
+
+    # Create a temporary lockfile
+    temp_lockfile <- "teal_app.lock"
+    file.create(temp_lockfile)
+    on.exit(if (file.exists(temp_lockfile)) file.remove(temp_lockfile), add = TRUE)
+
+    withr::with_options(
+      list(teal.lockfile.mode = "enabled"),
+      {
+        shiny::testServer(
+          app = srv_teal_lockfile,
+          args = list(id = "test"),
+          expr = {
+            # The server should detect existing lockfile and enable download
+            testthat::expect_null(session$returned())
+          }
+        )
+      }
+    )
+
+    # Clean up
+    if (file.exists(temp_lockfile)) file.remove(temp_lockfile)
+  })
+
+  testthat::it("returns NULL in auto mode when in disabled scenario", {
+    withr::with_options(
+      list(teal.lockfile.mode = "auto"),
+      {
+        # In test environment, .is_disabled_lockfile_scenario() returns TRUE
+        shiny::testServer(
+          app = srv_teal_lockfile,
+          args = list(id = "test"),
+          expr = {
+            testthat::expect_null(session$returned())
+          }
+        )
+      }
+    )
+  })
+
+  testthat::it("handles default empty mode option", {
+    withr::with_options(
+      list(teal.lockfile.mode = NULL),
+      {
+        # Default mode is "" (empty string)
+        # In test environment, .is_disabled_lockfile_scenario() returns TRUE
+        # so it should return NULL
+        shiny::testServer(
+          app = srv_teal_lockfile,
+          args = list(id = "test"),
+          expr = {
+            testthat::expect_null(session$returned())
+          }
+        )
+      }
+    )
+  })
+
+  testthat::it("accepts valid mode values: auto, enabled, disabled", {
+    # Test 'disabled' - doesn't need mirai/renv
+    withr::with_options(
+      list(teal.lockfile.mode = "disabled"),
+      {
+        testthat::expect_silent(
+          shiny::testServer(
+            app = srv_teal_lockfile,
+            args = list(id = "test"),
+            expr = {}
+          )
+        )
+      }
+    )
+
+    # Test 'auto' - in test env, should be disabled
+    withr::with_options(
+      list(teal.lockfile.mode = "auto"),
+      {
+        testthat::expect_silent(
+          shiny::testServer(
+            app = srv_teal_lockfile,
+            args = list(id = "test"),
+            expr = {}
+          )
+        )
+      }
+    )
+  })
+})